Cashews are the seeds of the cashew tree, Anacardium occidentale, native to Brazil. The seeds are often mistakenly classified as nuts, and most cooks treat cashews like nuts, especially since they behave like nuts in the kitchen. For people with allergy issues, the distinction between nut and seed can be very important, as some people who are allergic to nuts are not allergic to cashews.
The cashew tree was used as a source of food by Native Americans long before it was discovered by European explorers, who brought the bizarre crescent shaped cashew seeds back to Europe with them. The cultivation of cashews on a small scale began in Europe, but spread into Asia and Africa. India is a major cashew producing nation, and several African countries contribute large crops as well. The name for the seeds is derived from acaju, a Portuguese word which refers to the cashew tree.
The parent tree often resembles an oversized shrub, since the limbs tend to cling close to the ground, and will sometimes re-root themselves if the tree is not attentively cared for. The tree generates clusters of white to pink flowers which develop drupes, seeds enclosed by a fleshy outer layer. As the drupes mature, the cashew tree creates a cashew apple, a pear shaped fruit ranging in color from yellow to red. The cashew apple develops between the drupe and the tree, and when both have matured, the cashew seed ends up dangling from the end of the drupe.
The remarkable appearance of mature cashews must have captivated people who first saw the trees. Before consumption, the cashew seed must be carefully removed from the drupe, since the outer layer is toxic and can be dangerous. This is done by roasting or soaking the cashews, which will split the outer casing to expose the seeds. Until the seeds have been extracted, the drupes must be handled with care, since workers have been known to develop skin rashes and other conditions in response to exposure.
Cashews have a very high fat content, which can lead them to go rancid quickly. The seeds also have a mild buttery flavor and an oily mouthfeel. The cashews can either be processed for sale whole, or ground into cashew butter, a rich creamy spread which can be used like peanut butter. Whole cashews are often used in savory dishes, or eaten plain by fans of the seeds.